Roasting-furnace construction



2 Sheets-Sheet May 15, 1928.

D. BAIRD RoAsTING FURNACE coNsTRUcTIoN Filed oct. 8, 1926 35% @bio/w May 15, 1928. -i69925 D. BAIRD ROASTING FURNACE CONSTRUCTION Filed oct. 8, 1926 2 sheets-sheet 2 Patented Muay l5, 1928.

UNITED STATES PATENT oFFlcE".

DUDLEY BAIRDQOF BERKELEY, CALIFORNIA, ASSIGNOR TO NICHOLS COPPER COM- Pm, OF NEW YORK, 42N. Y., ACORPORATION 0l' NEW YORK.I

Rosanne-remmen coNsmwc'rIoN..

Application led October 8, 1926. Serial No; 140,230.

This invention relates to roasting furnaces and more particularly -to` multiple hearth rotating shaft furnace constructions.

-In furnaces of this t pe having a yhollow rotatable shaft with hoilow rabble arms extending therefrom, it is customary to prouvide conduits within the shaft and arms for controlling the circulation therethrough of a coolin uid such as air. In some instances itliculty has heretofore been experienced in providing a suitable joint or hub portion for interconnecting the rabble arms and the conduits therein with the rotatable shaft andpits conduit or conduits. Accordingly it is an object of this invention to provide an improved, inexpensive, and durable form of rabble arm and shaft hub construction, with improved means therein for interconnecting the conduits of the arms and shaft.

Various further specific objects, features and advantages will more clearly appear from the detailed description given below taken in connection with the accompanying drawings which form a part of this specification.

In the drawings, Fig. 1 represents a vertical sectional view partly broken away and taken substantially along the vertical axis of a furnace construction embodying the invention;

Fig. 2 is a top or plan view showing the end portion of a rabble arm embodying features of the invention;

i F ig. 3 is a vertical sectional view taken through the end portion of a rabble arm such as shown in Fig. 2;

Fig. 4 is a longltudinal sectional view taken substantially along the section line 4 4 ofthe rabble arm indicated in Fig. 3;

Fig. 5 is a transverse sectional view taken substantially along the section line 5-5 indicated in Fig. 3; p

Figs. 6, 7 and 8 respectively are other transverse sectional views taken substantially along the section lines 67 and `8v of Fig. 9 is a sectional view taken substantially through the axis of a portion of a hollow rotatable shaft member of a roasting furnace embodying the invention;

Fig. 10 is an elevational view of the portion 0f e .member es, shown in Fig. e;

Fig. 11 is a transverse sectional view taken substantiallyalong the line 11-'-11 indicated in Fig. 9;

Fig. 12 is a sectional view taken substantially along the section line 12-.12 indicated in Fig. 9; and y Fig. 13 is a central sectional View illustrating a portion of a modified form of shaft construction embodying certain features of the invention.

In the furnace as shown in Fig. 1 a plurality of vertically spaced or superposed and substantially circular hearths are provided as at 2O and 21. These hearths are surrounded and supported in the conventional manner by .a substantially cylindrical furnace wall 22. A rotatable and internally cooled central shaft 23 extends vertically up lthrough the furnace substantially along the central aXisthereof and is provided with a series of rabble arms as at 24 and 25 eX- tending radially from the shaft into the spaces between succeeding hearths. Suitable rabble teeth 26 are-provided along each-- novel features of construction embodied in p rying the rabble teeth and the inner member 28 comprising a conduit for controlling the circulation of cooling fluid within the arm. It will be noted that the outer member has a cross-section substantially larger than the inner member and that the two members are thus spaced apart by an annular passagelway 29, which may receive the circulating cooling fluid. The tubular member 27 may be provided at 30 with a bearing area which is preferably but` not necessarily relatively .bular member 2.7y is extended and may be formed with a restricted or substantially conical end portion 31 which is tapered down in the particular construction shown to such a diameter that its peripheral edges at 32 closely embrace and may be jo1ned to the corresponding peripheral edges at the inner] end of the conduit 28, (see Fig. 4). Of course, according to some phases of the invention the end portion of the arm need not be restricted or conical. The inner end of the conduit is thereby securely held in position with its walls substantially concentric with the outer tubular member. Except for the inner end portion of the conduit 28, its walls may be thus substantially spaced from the body member of the rabble arm and accordingly uniform heat radiation and cooling of the inside walls of the rabble arm is not interfered with by the presence of the conduit. It will be noted that the conduit joins the outer tubular member at a point wholly within the limits of the walls of the rotatable shaft and accordingly the joint is protected fromthe high temperatures prevailing outside the central shaft. The portion 31 may be formed with suitable large pcrforations or openings as at 33 and 34, (see Fig. 4), which provide passages perlmitting the cooling fluid to freely circulate from the annular passage 29 out of the rabble arm into the central shaft. At the same time sutlicient wall area remains in the portion 3l to provide ample strength as is indicated in- Figs. 6 and 7.

The central shaft 23 may be formed in sections as of cast iron, each section terminating in suitable flanges as at 35 (see Fig. 9), and the cooperating flanges of adjacent sections may be bolted together in any suitable known manner. Inside of each section and preferably substantially concentric or generally symmetrical with the outer section walls, a cooling fluid :conduit 36 may be formed. This conduit may include web portions extending to the outer walls of the shaft 23 and may thus be cast integrally with the section vas indicated in Fig. 11 or formed otherwise, if desired. This integral construction affords great strength for the rabble arm bearing supporting areas and insures proper alignment of the apertures at the bearings as hereinafter referred to. At

each point where rabble arms are to be attached, the cross-sectional area of the outer passageway or .passageways of the central shaft are preferably substantially enlarged in respect to other parts of the passageway and the cross-sectional area of the interior conduit at such points. This to a certain degree compensates for the volume taken up by the end of the rabble arm protruding into the shaft at these points and at the same time affords free communication between the rabble arm openings and the shaft spaces and this also permits greater separation of the two bearing areas for the rabble arms, thus insuring greater-rigidity- For example, in the form illustrated, the section is provided with a hollow protuberauce as at 37, which is substantially in the shape of a truncated cone terminating in a narrow bearing area 38 for encircling and engaging the rabble arm bearing area 30. It will be noted that with the rabble arm in position as shown in Fig. 1, the walls of the protuberance 37 are substantially spaced from the rabble arm except at the narrow bearing area. The hollow protuberance being filled with the circulating cooling fluid, a uniform cooling action over all the portions of the hub area is insured. The walls of the shaft section and of the hollow protuberance are preferably of substantially uniform thickness throughout as shown and are free from reinforcing ribs, thickened spots, etc., which further contributes to the same result. The conical shape of the protuberance 37 also insures ample bracing for the bearing area 38, rendering unnecessary the use of reinforcing ribs. The elimination of reinforcing ribs and the like not only results in a saving of material and reduction of weight, but also prevents non-uniform temperature conditions and the consequent destructive forces and strains which tend to arise within thick metal parts of irregular dimensions.

Opposite each of the protuberances 37 the conduit 36 may be provided with suitable openin s or sockets having bearing areas 39 for em racing the peripheral edges at the end of rabble arm members, at the same time the opening provides communication between the conduit 36 and the rabble arm conduit 28. With this construction two widely spaced bearings areas 38 and 39 are provided for each rabble arm and in view of this spacing such bearings need be only narrow areas (although not necessarily so in all cases) offering substantially a minimum amount of inter erence with the thorough cooling of the interior surfaces of the shaft sections and rabble arms.

The bearing area 3() may be provided with an opening 40 for registration with an openingll formed in the bearing 38. The rabble arm may be removably secured in position on the rotatable shaft by inserting a retaining pin 42 through the openings 40 and 41 in the usual manner. The rabble arm and bearing portion 38 respectively may be formed with cooperating wedge portions 43 and 44 for securely fixing the rabble arm in proper alignment.

When the furnace is in operation with the j central shaft assembled .with its rabble arms,

the pathof the cooling fluid is from the in- 'terior pf the' shaft conduit.L 36 through the openings at 39 into the rabble arm conduits 28 to the end ofthe rabble arms. The coolspac'es 2)and is thereby returned to the inner ends ofthe rabble arms, and allowed 'to flow therefrom through vthe openings 33 and 34. With the constructions as described the openings 33 and. 34 maybe made of ample size-to permit the Ifluid to freely flow therethroi1 gh out of either side of the arm into the hollow protuberances or equivalent enlar ements of the cross-section of the shaft cavit e at these ints, and up the central shaft' through t e outer space 45. Heretolfore it has been necessary 1n many cases to use a central shaft of a diameter larger than is necessary with the present invention merely to provide space for suitable discharge openings from the rabble arms. The excessive waste of space andrr` material necessary for such a large central' shaft has, by this invention, been eliminated. At the same time a construction is provided in which a substantially maximum possible interior wall area of each part is directly exposed to the circulating cooling fluid. Owing to the fact that the Shaft sections and the rabble arms are exposed at their outer surfaces to the` high temperatures encountered in the roasting and calcining ofores and other materials, it is necessary to properly anduniformly cool these parts to prevent buckling or destructive cracking. In the structure here shownfor substantially all of the areas exposed to heat a corresponding internal area exposed to cooling air is provided. Hence, uniform and' efficient radiation from the heated surfaces is obtained and substantially no unequal strains in the metal parts due to heating can arise.

While the rhollow protuberances 37 in the preferred embodiment above described are of a substantially conical shape except where modified for mechanical reasons, it will be understood that various phases of the in- I'vention are also applicable to such prot-uberances which are not conical. For example, in Fig13 a portion of a shaft section wall 46 is shown provided with a substantially cylindrical or oval protuberanee or cavity enlargement 47 formed integrally with the wall 46 or otherwise secured thereon. An interior shaft conduit 48 similar to the conduit 36 is also provided and formed with a bearing area 49 which, in cooperation with a. bearing area 50 within the protuberance 47, provides for engagement with a suitable rabble arm. 4 l

While the invention has been described in detail'with respect to certain particular preferredexamples which give satisfactory results, it will be understood by those skilled in the arty after understandin the inventiom that various changes and modifications may be made without departing from the spirlt' and scope .of the inventiontand vit is intend-V g l x ed, therefore, in the appended claims to cover ing fluid 1s then conducted to the annular p shaft and joined with conduits through said arms for controlling the flow of cooling fluid within` the shaft and arms, the walls of said' hollow shaft being formed with annular hollow protuberances within each of which one of said arms is received and removably secured, the walls of said hollow arms tapering so as to closely embrace said arm conduits at their inner ends inside said protuberances, and openings being formed through the tapering wall areas ofsaid arms whereby cooling fluid may freely flow from the hollow arms through said openings and hollow protuberances into the hollow shaft.

-2.\In a roasting furnace, a rotatable hollow shaft with hollow rabble arms extending. therefrom, conduits extending through said shaft and joined with conduits through said arms for controlling the flow of cooling said hollow protuberances wherebyf cooling fluid Amay freely flow from the hollow arms through said'openings and hollow protuberances into the hollow shaft. t

3. A hollow rotatable shaft member for roasting furnacesv having substantially conical and relatively lthin walled hollow pr`otuberances thereon, each terminating in annular bearing areas for embracing a rabble arm extending into the shaft through the protuberance. Y

4. A hollow rotatable shaft member for roasting furnaces having hollow protuberances thcreon, an opening being formedV through each of said protuberances for receiving a rabble arm. the walls of each pro' tuberance being spaced from the area occupied by the rabble arm except for a narrow bearing area encircling the arm at said opening.

5. A hollow rotatable shaft member for roasting furnaces having` hollow protuberances thereon, an ,opening being formed through each of said protuberances for receiving a rabble arm, thewalls of each protuberance being spaced from the area occupied by the rabble arm except for a narrow,

ing fluid conduit within said shaft member and having openings opposite sai@ openings iirst named for receiving the ends of the rabble arms. w

6. A hollow rotatable shaft member for roasting furnaces having hollow protuberances thereon, each terminating in annular bearin areas for embracing a rabble arm extending into the shaft through the protuberance and spaced from its walls, the

walls of said member and protuberancesl being of substantially uniform thickness throughout for the purposes described.

7. A hollow rotatable shaft member for roasting furnaces having hollow protuberances thereon, each terminating in annular bearin extending into the shaft through the protuberance and spaced from its walls except at said bearing areas, the -protuberances being of a substantially conical shape to pro# vide a strong bearing supporting means free from reinforcing ribs, thickened areas,`etc.

8. In combination` a roasting furnace arm comprising a tubular body member for carrying rabble teeth, a bearing area encircling the supported end of said member, a restricted and perforated end portion beyond said bearing area, a coolin fluid conduit extending within said bo y member and having its peripheral edges at one end embraced b v and joined to the peripheral edges of said restricted end portion of the body member, the walls of the conduit and body member being otherwise substantially spaced apart, and a hollow rotatable Vshaft member having a substantially conical hol-v low protuberance thereon terminating in a relatively restricted portion comprising a'n annular bearing area for tting the rabble arm bearing area.

9. In a roasting furnace` a rotatable hollow shaft with hollow rabble arms extending therefrom, conduits extending through said shaft and joined with conduits through said arms for controlling the flow of cooling fluid within the shaft and arms, the walls of said hollow shaft being formed with annular hollow protuberances within each of which one of said arms is received and removably secured,`the walls of said hollow arms closely embracing said arm` conduits at their inner ends inside 'said protuberances, and openings being formed through the wall areas of said arms adjacent their inner ends whereby cooling fluid ma freely flow from the hollow arms throug said openings and hollow protuberance's into the hollow shaft.

10. In combination, a roasting furnace arm comprising a tubular body member for carrying rabble teeth, a bearing area encircling the supported end of said member a restricted and perforated end portion yond said bearing area, a cooling fluid conareas for embracing a rabble arm' duit extending within said body member and havin its peripheral, edges at one end embrace by and joined to the peripheral edges of saidl restricted end portion of the body member, the walls of the conduit and body member being otherwise substantiall spaced apart,and an arm supporting member having an enlarged hollow socket portion terminating in an annular bearing area for fitting the rabble arm bearing area.

11. In a roastin furnace, a rotatable hollow shaft with ho ow rabble arms extendin therein, conduit means extendin1r within sai shaft and joined in communlcation with conduits through said arms for controlling the flow of coolin fluid within the shaft and arms, the conduit means in said shaft including an inner tubular member cast integrally with web portions integral with the outer shaft walls, and an outer tubular passageway or spaces provided between said inner tubular memberand the outer shaft walls, said rabble arms extending through bearing apertures in the outer shaft wall and into engagement with bearing apertures within the inner tubular wall, the cross-sectional area of the outer tubular spaces of the shaft being substantially enlarged at the points where the rabble arms protrude therein, whereby space is made available for free communication between openings to the rabble arm conduits and outer shaft spaces.

12. A hollow rotatable shaft member for roasting furnaces having an inner tubular conduit means for cooling fluid, outer conduit spaces being provided between said means and the shaft walls, and rabble arms protruding through said outer shaft walls and into engagement with the inner tubular means, the aggregate cross-sectional area of said outer conduit spaces being greater adjacent said inwardly protruding rabble arms.

13. A hollow shaft member for roasting furnaces having an inner tubular conduit means for cooling fluid, outer conduit spaces being provided between said means and the shaft walls, and rabble arms including internal cooling conduits protruding through said outer shaft walls and into engagement with the inner tubular member, said outer spaces including enlarged cavities at the points where said rabble arms protrude into the shaft whereby to `compensate for the volume of the shaft end's at such points and to afford free communication between the rabble arms and outer shaft spaces.

14. A hollow shaft member for roasting furnaces having an inner tubular conduit means for cooling fluid, outer conduit spaces being provided between said means and the shaft walls, and rabble arms including internal cooling conduits protruding through said outer shaft walls and into engagement with the inner tubular member, said outer spaces including enlarged cavities at the lll) points where said rabble arms protrude into the shaft whereby to compensate for the volume of the'shaft ends at such points and tov aiord free communication between the rabble arms and outer shaft spaces, and web members cast integral with saiddinner tubular means and the outer shaft walls and straddling such enlarged cavities.

15. In apparatus of the class described, a cooling fluid supply shaft provided exteriorly with a seat and with an opening surrounded thereby, an enclosing exhaust fluid conducting shaft having an opening opposite the seat, a rabble arm including an outer tubular member fitted at its inner end through the opening in the exhaust fluid conducting shaft and into the seat, andan inner tubular member in communication with the cooling fluid supply shaft and with the interior of the'outer member, the crosssectional area of said exhaust fluid conducting shaft being substantially greater adjacent'said rabble arm as compared with its cross-sectional area at other points.

In testimony whereof I have signed my name to this specification.

DUDLEY BAIRD. 

